This invention generally relates to a safety apparatus for a motor vehicle such as an automobile and particularly to an apparatus for inflating a cushion or air bag with gas upon collision of the vehicle.
Inflatable bag restraint systems have been shown to reduce the seriousness and number of fatalities resulting in motor vehicle accidents. There exists a number of means for inflating an air cushion or air bag such as utilizing a quantity of stored gas which is selectively released to expand the air bag. Alternatively, a gas source derived from a gas generating material propellant such as sodium azide, which upon ignition thereof generates a sufficient quantity of gas to expand the air bag. The third type of gas source results from a combination of the stored compressed gas and a gas generating or enhancing material. This last device is often referred to as an augmented gas or hybrid inflater. Various hybrid inflaters have been shown in the past such as those illustrated in U.S. Pat. Nos. 3,756,621 and 3,895,821. The inflater shown in U.S. Pat. No. 3,756,621 uses a separate squib or initiator to ignite the propellant and an actuator to open an exit passage to initiate compressed gas flow. U.S. Pat. No. 3,895,821 mounted a single squib outside the pressurized environment of the pressure vessel to ignite the propellant. In the present invention, a single squib and propellant chamber or housing is placed in a compressed inert gas environment. Upon initiation of the propellant, a heated media is generated comprising hot gas and particulates which are directed by a discharge nozzle into a small mixing cavity or chamber adjacent a rupturable disk causing same to burst, initiating gas flow into an air bag. Hot gases continue to be emitted from the propellant chamber and mix with the cold pressurized gas in a small mixing chamber before continuing into the bag to inflate same. The present invention yields an advantage in relation to the prior art in that the number of leak passages are reduced, a faster onset of gas flow is achieved, and by placing the propellant and squib within the compressed gas, yields an improved (dry) environment for the protection of the propellant and squib.
It is an object of the present invention to provide a hybrid inflater which can rapidly and efficiently generate a sufficient quantity of gas to inflate a cushion or air bag during a vehicle crash situation.
Accordingly, the invention comprises an inflater for a cushion or air bag comprising: pressure vessel means for storing a volume of inert gas at an elevated pressure, including at least one opening adapted to communicate gas within the pressure vessel to a cushion. A mixing chamber is provided directly upstream of the nozzle defining a volume significantly smaller than the remaining volume of the pressure vessel. A rupturable disk is placed at one end of the heated mixing chamber for opening the pressure vessel and generating means responsive to a control signal generates a quantity of generated heated media (gas flame and/or some particulate matter) which impinge directly as the disk weakening same to the point of rupture. The heated media mixes with the stored gas increasing its volume to supplement the pressure of the stored gas in effect to supplement the pressure of the stored inert gas.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.